The present disclosure relates to toners suitable for electrophotographic apparatuses and processes for making such toners.
Numerous processes are within the purview of those skilled in the art for the preparation of toners. Emulsion aggregation (EA) is one such method. These toners may be formed by aggregating a colorant with a latex polymer formed by emulsion polymerization. For example, U.S. Pat. No. 5,853,943, the disclosure of which is hereby incorporated by reference in its entirety, is directed to a semi-continuous emulsion polymerization process for preparing latex by first forming a seed polymer. Other examples of emulsion/aggregation/coalescing processes for the preparation of toners are illustrated in U.S. Pat. Nos. 5,403,693, 5,418,108, 5,364,729, and 5,346,797, the disclosures of each of which are hereby incorporated by reference in their entirety. Other processes are disclosed in U.S. Pat. Nos. 5,527,658, 5,585,215, 5,650,255, 5,650,256 and 5,501,935, the disclosures of each of which are hereby incorporated by reference in their entirety.
Polyester EA ultra low melt (ULM) toners have been prepared utilizing amorphous and crystalline polyester resins. Some of these toners may have poor charging characteristics, which may be due, in part, to the presence of coarse particles. For example, while a circularity of greater than or equal to about 0.96 may be desirable, in embodiments the processes utilized to achieve this circularity, which may include heating the particles at a temperature below the melting point of the crystalline resin (in embodiments less than about 70° C.), may result in the formation of toners having a large number of undesired coarse particles, in some cases coarse particles may be present in an amount of from about 10% to about 15% by weight of the toner particles. Improved toners and processes for producing these toners thus remain desirable.